Magnetic properties of some Cu-containing phosphates

Abstract Magnetic susceptibility and specific heat measurements are presented for some Cu-containing phosphates with different copper frameworks, M 2 Cu(PO 4 ) 2 (M=Sr and Ba: linear 1D uniform chains), BaCuP 2 O 7 (double 1D uniform chains), MCuP 2 O 7 (M=Ca, Sr, and Pb: zig-zag 1D uniform chains), and Sr 9.1 Cu 1.4 (PO 4 ) 7 (isolated Cu 2+ ions). We observed short- and long-range magnetic ordering in these compounds in which the main Cu–Cu interactions are transferred through PO 4 groups. In M 2 Cu(PO 4 ) 2 and BaCuP 2 O 7 , J / k B values of about 100–140 K and k B T N / J